Time interval between breast cancer diagnosis and surgery is associated with disease outcome

Time interval between breast cancer (BC) diagnosis and surgery is of concern to patients and clinicians, but its impact on survival remains unclear. We identified 5130 BC patients receiving surgery between 2009 and 2017 from the Shanghai Jiaotong University Breast Cancer Database (SJTU-BCDB), and divided as Ruijin cohort and SJTU cohort. All participants were divided into three groups according to the interval between diagnosis and surgery: ≤ 1 week, 1–2 weeks, and > 2 weeks. Among 3144 patients of Ruijin cohort, the estimated 5-year breast cancer-free interval (BCFI) rates for the ≤ 1 week, 1–2 weeks and > 2 weeks groups were 91.8%, 87.5%, and 84.0% (P = 0.088), and the estimated 5-year overall survival (OS) rates were 95.6%, 89.6%, and 91.5% (P = 0.002). Multivariate analysis showed that patients with a TTS > 2 weeks had significantly lower BCFI (HR = 1.80, 95%CI 1.05–3.11, P = 0.034) and OS (HR = 2.07, 95% CI 1.04–4.13, P = 0.038) rates than patients with a TTS ≤ 1 week. Among 5130 patients when combining Ruijin cohort with SJTU cohort, the estimated 5-year BCFI rates for the ≤ 1 week, 1–2 weeks, and > 2 weeks groups were 91.0%, 87.9%, and 78.9%, and the estimated 5-year OS rates for the ≤ 1 week, 1–2 weeks, and > 2 weeks groups were 95.8%, 90.6%, and 91.5%, both with a significantly p value < 0.001. Our findings demonstrated the prolonged time to surgery (more than 2 weeks) after BC diagnosis was associated with poor disease outcomes, suggesting that efforts to early initiate treatment after diagnosis need to be pursued where possible to improve survival.

Patient's clinicopathological features. The collected data included patients' sociodemographic factors (residence area, education level), clinicopathological characteristics (age, menopausal status, comorbid condition, tumor stage, pathological type, histologic grade, body mass index (BMI), hormone receptor (HR) status, HER2 status, lymphovascular invasion (LVI), Ki67 index, and molecular subtype) and details of treatment (breast surgery, radiotherapy, chemotherapy, endocrine therapy, and HER2-targeted therapy). Tumor stage was based on pathologic criteria according to the seventh edition of the American Joint Committee on Caner (AJCC) TNM staging system 15 . Comorbid condition was evaluated by using the Charlson Comorbidity index (CCI) and divided into 0, 1-2 or 3 + 16 . Prolonged time to chemotherapy (TTC) was defined as the interval from surgery to chemotherapy > 6 weeks. Prolonged time to radiotherapy (TTR) was defined as interval from surgery to radiotherapy > 32 weeks for those patients receiving chemotherapy, or > 12 weeks for those patients not receiving chemotherapy.

Interval between diagnosis and surgical treatment initiation. The interval between diagnosis
and surgical treatment initiation was defined as the time from pathological diagnosis to the definite surgery. Pathological diagnosis was made by core needle biopsy (CNB). The interval of TTS was categorized as ≤ 1 week, 1-2 weeks, and > 2 weeks.
The diagnostic and surgical procedures are as followed: Patients with suspicious breast lesion will be scheduled for hospitalization after outpatient consultation. After the hospitalization, the radiologists will involve to perform image assessments and lesion localization. Patients will receive core needle biopsy after image assessments finished. Breast surgeons do the core needle biopsy. The primary pathological results will be presented in 1-2 days after CNB by our pathologists with malignant or benign diagnosis. The receptor status by Immunohistochemistry (IHC) testing will be reported in another 2 days after primary diagnosis result. Majority of patients will receive surgery after receiving pathological diagnosis with or without IHC result.

Follow-up.
For all patients, outpatient visits or telephone calls were performed every 3 to 6 months until death. The primary endpoint was the breast cancer-free interval (BCFI), which was defined as the length of time from surgery to the first occurrence of the following events: locoregional recurrence of any invasive disease, contralateral invasive BC, distant recurrence, and BC-related death. The secondary endpoint was overall survival (OS), which was defined as the length of time from surgery to any cause of death. www.nature.com/scientificreports/ Statistical analyses. Distributions of patient sociodemographic, clinicopathological, and treatment characteristics by TTS intervals were examined using χ 2 or Fisher's exact tests. We evaluated the association between TTS and survival using Cox proportional hazards regression models. Prognostic factors with significant or marginal p values (P < 0.1) in the univariate analysis were included in the multivariate analysis. Planned subgroup analyses included the Cox models according to the age at diagnosis, molecular subtype, tumor stage and radiotherapy. Two-sided P values < 0.05 were considered statistically significant. Statistical analyses were conducted with IBM SPSS version 20 (SPSS Inc., Chicago, IL, USA). We performed propensity score matched (PSM) analysis in the combination of Ruijin & SJTU cohort by using R program version 3.6.3. The command matched 5 patients with TTS ≤ 1 week to one patient with 1-2 weeks and one patients with TTS > 2 weeks using factors including age, CCI, tumor stage, molecular subtype, pathological type, tumor grade and surgery type, and the caliper value of PSM was 0.2.
Ethical approval. All data was obtained from SJTU-BCDB database. This study was conducted in accordance with the Declaration of Helsinki, and approved by the independent Ethical Committees of Ruijin hospital. Given the anonymised nature of the data, the requirement for informed consent was waived by the independent Ethical Committees of Ruijin hospital.

Results
The Ruijin cohort. Patient characteristics. A total of 7023 patients underwent curative surgery for BC at Ruijin Hospital between January 2009 and December 2017. Finally, 3144 patients were included (Fig. 1). The median time from pathological diagnosis to surgery was 4 days (range from 0 to 59 days) (Figs. S1, S2a). Patients who received surgery within ≤ 1 week, 1-2 weeks, and > 2 weeks after diagnosis accounted for 90.9%, 5.6%, and 3.5% of all patients, respectively.
Association between TTS and clinicopathological characteristics. Descriptive results according to TTS are detailed in Table 1. The mean age of all participants in this study was 55.9 years. Regarding the demographic characteristics, patients with a prolonged interval (> 2 weeks) were more likely to be aged > 70 years old (P < 0.001) and to have CCI more than 3 (P < 0.001). Residence area, education level, and BMI were not associated with a prolonged interval between diagnosis and treatment initiation (P > 0.05). When calculating the change in the Ki67 index by TTS, patients with TTS greater than 2 weeks had a significantly higher Ki67 increase than patients with TTS less than 2 weeks (7.3% vs. 4.0%, P = 0.022) (Fig. S3). In addition, clinicopathological features, such as tumor stage, tumor grade, operation type, and molecular subtype, also did not differ according to TTS. The relationships between TTS and adjuvant treatment are shown in Table 2. Statistical significance was only found between prolonged interval and adjuvant chemotherapy (P = 0.009). And there were not statistical significant relationships between TTS and prolonged TTC (P = 0.120) nor prolonged TTR (P = 0.567).
Disease outcome. The follow-up ranged from 1 to 128 months, with median follow-up duration of 52 months and 247 BC-related events. The estimated 5-year BCFI rate was 91.4%, and univariate analyses of the BCFI by prognostic factors are presented in Table 3. Patients' clinicopathological characteristics, such as tumor size, axillary node status, tumor stage, histological grade, LVI, ER status, PR status, and molecular subtype, were all significantly correlated with the BCFI (p < 0.05), and age was marginally significant (p = 0.053) (Fig. S4). Regarding   www.nature.com/scientificreports/ node status, tumor stage, histological grade, LVI, ER status, PR status and molecular subtype (p < 0.05) ( Table 3). In contrast, comorbid conditions, residence areas, education levels, chemotherapy and radiotherapy had no significant association with the OS (P > 0.05).
Association between TTS and BCFI according to clincopatholigcal characteristics. To further identify which patient population with a prolonged TTS had the worst BC-related survival, subgroup analyses including prognostic factors with significant or marginal p values in the multivariable model were performed (Table 5). The interaction p between molecular subtype (P < 0.001), tumor stage (P < 0.001), radiation (P = 0.003) and TTS reached statistical significance. In contrast, the interaction p between age and TTS did not reach statistical significance (P = 0.875).
Among different subtypes, patients with HER2 disease (HR 3.66, 95% CI 1.47-9.12, P = 0.001) had a significantly poor BCFI rate when having more than 2 weeks prolonged interval between diagnosis and surgery (Fig. 3). Similarly, patient with stage I tumors, and without radiation had a significantly poor BCFI rate when having TTS > 2 weeks (Table 5, Fig. 3).
The SJTU cohort. Patient characteristics. Besides BC patients of Ruijin Hospital, a total of 1986 patients were included from SJTU-BCDB database, and identified as the SJTU cohort. The median time from BC diagnosis to surgery was 4 days (range from 0 to 89 days). Patients who received surgery within ≤ 1 week, 1-2 weeks, and > 2 weeks after diagnosis accounted for 74.9%, 18.2%, and 6.9% of all the patients, respectively (Fig. S2b). Descriptive results according to TTS are detailed in Table 6.  Table 7).

Discussion
The hypothesis exists that prolonged interval from pathological biopsy to surgery might allow BC cells to proliferate and spread to other sites, which causes the impaired prognosis 17 . However, there has been little consensus about the relationship between prolonged surgical initiation and BC patient survival, especially in the era of modern treatment of BC. To our knowledge, the present study has both the largest single institute cohort (Ruijin cohort) and multicenter cohort (Ruijin cohort plus SJTU cohort) to examine the association between prolonged time to surgery and early stage breast cancer prognosis in modern era of adjuvant treatment. We found that long interval from biopsy to definite surgery is associated with worse BCFI and OS, providing evidence that patients with a prolonged TTS (> 2 weeks) after BC diagnosis may experience poorer survival than patients who undergo surgery with short TTS. A consistent trend between greatly long interval (e.g. > 4 weeks) and inferior survival was also observed in our study. According to these results, the efforts to shorten TTS for BC patients are extremely necessary. Furthermore, we found that several factors, including age and comorbid conditions, are correlated to prolonged interval to BC surgery, and the elevated recurrence risk associated with prolonged TTS may vary by the tumor subtype, tumor stage, and radiation treatment.
Concerning the factors related to prolonged TTS, time to surgery is affected by the cancer care pathway from diagnosis to making appointment(s) and treatment. In clinical scenario, an adequate time is needed for treatment planning before definite surgery, such as pathology and imaging assessments [18][19][20][21] . Besides this, the time spent waiting for receptor testing and considering neoadjuvant chemotherapy to shrink operable tumors would also prolong TTS. In addition, the preoperative genetic testing or planning for oncoplastic surgery may also largely contribute to long interval between pathological biopsy and surgery 22 . Regarding patients' factors, patients may also prolong decision making by seeking multiple opinions or request delays to accommodate their work or personal schedules. Other factors, such as patient's anxiety, age, comorbid conditions, and some sociodemographic factors (e.g. patient's education level and residence area), can also confer additional delays [23][24][25][26][27] . Furthermore, since 2020, challenges from the COVID-19 pandemic, including the risk of patient and staff exposure to SARS-CoV-2 and the need for personal protective equipment, ventilators, and medical staff who could otherwise be deployed to care for patients with COVID-19, would also prolong TTS 28,29 .
Our study found that long interval to surgery would impair patient's disease outcome, which was consistent with other studies. Eaglehouse et al. reported a significantly increased risk (30%) of all-cause death with a Table 5. Exploratory analyses of BCFI rates by time to surgery after diagnosis according to patient characteristics and tumor subtype, The Ruijin cohort. *p < 0.05 compared with ≤ 1week group.  8 , which found that the 5-year OS rate in patients with TTS ≥ 6 weeks (80%) was significantly lower than that patients with TTS less than 2 weeks (90%). Moreover, Bleicher et al. found a significantly increased risk (10%) of all-cause mortality for each incremental 30-day interval between diagnosis and surgery and a 26% higher risk of BC-specific mortality for each 60-day increase in TTS 9 . Nevertheless, several studies have shown no association between a prolonged interval and survival 30,31 . The possible reasons for the inconsistency were varied, and the bias of information from the cancer registry database might be one possible reason. Most of the above studies used nationwide cancer registry data as a data source, which tend to have limited details and may be inaccurate. In contrast, our study used electronic medical record data derived from a single institution (Ruijin cohort), which would contain more accurate clinicopathological information and survival data. Moreover, those reports included patients from twenty years ago, which has not integrated modern era treatment advances, including adjuvant anti-HER2 therapy and ovarian function suppression treatment, but our study included patients in recent ten years with these systemic treatment advances. Obviously, TTS reported in our study (median TTS: 4 days) was significantly shorter than that in the abovementioned studies, indicating the difference of patient care system between China and America or other countries. As Fig. S1 illustrated, we have explained our diagnostic and surgical procedure in methods. In China, due to our large patient population, the cancer care system needs accelerating treatment procedure to shorten the hospitalization time, and patients are also willing to be diagnosed and treated within a relative short time period 5,10,11 . Moreover, due to the care system, treatment cost is much higher covered by the medical insurance if patients are treated in the ward, so most of patients will receive image assessments, core needle biopsy and following surgery in the same hospitalization period, leading to comparatively short waiting period between diagnosis and treatment. Therefore, to our knowledge, this study is also the first study to evaluate the impact of prolonged TTS at weekly length scale on BC patient prognosis, which is really hard to conduct in other countries.
Regarding the relation between prolonged TTS and poor survival, one of possible reason may be the increased Ki67 index after diagnostic biopsy. We previously reported a significantly higher Ki67 expression value in surgical samples than in CNB samples, and BC patients with longer surgery waiting times after biopsy had a higher chance of Ki67 increases, which was possibly due to wound healing and a stromal reaction 32 . Although the Ki67 www.nature.com/scientificreports/ www.nature.com/scientificreports/ index, as a BC proliferation biomarker, has not been confirmed to worsen the disease outcome, its increase might reflect tumor progression 33 . In the exploratory analysis of our manuscript, we observed the relationship between increase of Ki67 and longer TTS. Of course, there was a consistence debate about the Ki67 heterogeneity in CNB sample, which warrants further study. Another reason that may explain the poor disease outcome for patients with a prolonged TTS is the difference in tumor immune microenvironment. One former study from Mathenge EG et al. found that CNB created a distinctly immunosuppressive tumor microenvironment with a higher frequency of myeloid-derived suppressor cells (MDSCs) accompanied by reduced CD4 + T cells, CD8 + T cells, and macrophages 34 . Our team also reported that TILs were significantly higher in surgical samples than in CNB samples, and the increasing of TILs were associated with a longer TTS and a worse BCFI, especially in HER2 + patients, consistent with our finding 35,36 . In addition, Mathenge EG et al. found that, in the mouse model, the impact of CNB includes creation of a pro-metastatic tumor microenvironment with elevated TGF-β/SOX-4-associated epithelial-mesenchymal transition (EMT) and significantly higher circulating tumor cells (CTCs) levels 34 . Therefore, the association between longer TTS and survival is more likely due to tumor biological behavior change rather than sample loco-reginal spread phenomenon. One reasonable hypothesis might be that CNB stimulates tumor cells proliferation, destroys the barrier, creates an immunosuppressive tumor microenvironment, increases epithelial-mesenchymal transition (EMT), and facilitates release of CTCs during TTS, all of which likely contribute to the development of distant metastases, and worsen the prognosis. Potential reasons for prolonged TTS and its effects on survival is warranted to be better researched.
Regarding the interaction between tumor subtypes, TTS and prognosis, we firstly found patients with stage I TTS had a worse disease outcome when having prolonged TTS, possibly due to the relatively lower baseline recurrence risk in these patients compared to those patients with stage II or III disease. Moreover, the interaction of TTS and prognosis were also observed in HER2 positive patients and those not receive radiation treatment, indicating the possible higher proliferation activation after CNB in HER2 positive tumor and lacking of local control in patients who not treated with radiation. Interestingly, the results from several studies have provided evidence that a long interval from surgery to adjuvant chemotherapy 37 or from chemotherapy to radiotherapy 38 might cause a poor prognosis in certain populations. Taken together, our data support that care pathway for BC patients with short time period between biopsy and surgery is important. Neoadjuvant systemic therapy in lieu of surgery may be a reasonable option for these patients if they need a long waiting time period for surgery, such as the COVID-19 pandemic 39 . For example, one recent study from UK found a clinically significant impact on cancer survival if delays to the 2-week-wait cancer pathway are extensive and prolonged 40 . Therefore, some groups and scientific societies have made practical recommendations to try mitigating the deleterious effect of COVID-19 pandemic on cancer care. Our study will be helpful to possible BC patient selection, treatments and schedules tailored according to BC patients and tumor criteria 40,41 .
The retrospective analysis is a limitation of this study. However, it is difficult to conduct a randomized trial to investigate the optimal TTS. In addition, this study did not evaluate the time interval between symptom presentation and diagnosis. Finally, subgroup analysis was performed on a relatively small sample size, which was another limitation, we can't conclude whether patients with longer surgery delay would be related with even worse disease outcome, or longer delay was positively linearly associated with worse disease outcome. Further research with more number of included patients is needed to evaluate the role of TTS in these subgroups of BC patients.

Conclusions
Our study found that BC patients with elderly age and medical comorbidities were more likely to have a prolonged interval between diagnosis and surgery initiation. Prolonged time to surgery (more than 2 weeks) after BC diagnosis was associated with poor disease outcomes, which may vary by tumor stage, molecular subtype, and radiotherapy, indicating we need to shorten the time interval between initiate diagnosis and surgery, thus to improve BC survival.

Data availability
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.